The story is focused on a young man named Boone, who is suffering from an unspecified mental disorder. He is consulting a psychiatrist named Decker. To Boone's horror, he is informed by Decker that he is responsible for the brutal murder of eleven people, the most recent of which was in the City of Calgary. Boone, however, has no recollection of the murders he has committed.

Boone initially tries to kill himself, but when this fails, he begins to believe he can save himself from prosecution. Midian, a semi-mythical city, appears in his dreams as a place that offers sanctuary to monsters, who are collectively known as the Night Breed. He starts trying to reach Midian, unaware of the truth behind the insidious events that set him on this course.

Boone eventually finds Midian, but he discovers that the town is deserted and that it in fact lies beneath a cemetery. Two of the Night Breed appear and attack him. One of them bites Boone, but he is able to escape. Boone returns to the abandoned town where he is confronted by Decker. Decker reveals that Boone is innocent of the killings and that Decker is the one who actually committed the murders, intending to use Boone as a scapegoat. Soon after, Boone is shot dead by Decker and the policemen, who were on his trail. Boone's body is then placed in a morgue, but mysteriously disappears.

After Boone's apparent death, his lover, Lori, travels to Midian after hearing of his corpse's disappearance. Along the way, she makes friends with Sheryl, who decides to accompany her. When they arrive at the cemetery, Lori encounters two of the Night Breed: a small child named Babette and her mother Rachel. Lori is refused entrance to Midian, and she and Sheryl return to a nearby inn. Sheryl takes Lori to a restaurant to meet her new boyfriend, who turns out to be Decker. Decker, who possesses a button-faced mask that houses his murderous personality, kills Sheryl, but Lori narrowly escapes. She returns to Midian with Decker in pursuit. She is saved by Boone, who appears above ground and reveals himself. Before he leaves, Boone sees Midian’s creator, Baphomet, who appears as a dismembered body within a large fire.

Boone and Lori are commanded to leave Midian and return to the hotel where Lori had stayed with Sheryl. They soon discover that Decker had been at the hotel and has killed many inside. The police arrive and Lori is able to flee. Boone degenerates into an animal state and is quickly arrested. Decker goes to the police himself and is able to convince them to go to Midian and capture or kill everyone living there.

Lori meets up with the Narcisse, a former human who, like Boone, traveled to Midian and became part of the Night Breed. They enter the jail where Boone is being held and help him escape. They return to Midian, which is overrun by the police who have killed or captured many of the Night Breed, forcing them out from the underground by setting it aflame. Boone and the others engage in a fight. He has his final confrontation with Decker and kills him. The police officers have either been killed or chased off, but Midian is completely destroyed. The surviving Night Breed bind up the parts of Baphomet and leave in search of a new home.

In 2013, small press publisher Fiddleblack released an "annotated, limited edition" of the novella, titled Cabal & Other Annotations. The hand-numbered books were limited to a run of 300 and contained a collection of essays from Barker-centric contributors such as Peter H. Gilmore and Nicholas Vince, as well as artwork by Barker himself and a sizable appendix of scholarly footnotes by horror philosopher Eugene Thacker.[1]